I'll readily admit that, while I aim to be impartial, this might be slightly influenced by the movie adaptations. But still-I've read this series multiple times and was part of "the HP generation"-I started #1 when I was 10 and #7 came out when I was 17, so I feel qualified to share my opinions.
  1. Prisoner of Azkaban (tie)
    Let's dive right in: We're introduced to Hogsmeade, the Marauder's Map, dementors + patronuses, Lupin, Sirius, James' history at Hogwarts, etc. Bonus: Gryffindor FINALLY wins the Quidditch Cup! Hermione slaps Malfoy, storms out of Divination, handles time-turner drama, etc. And for a few sweet pages, we think that Harry is going to be able to leave the Dursleys and have a normal home life. Alas, this flame is snuffed out as soon as it's lighted, but it was fun while it lasted.
  2. Half-Blood Prince (tie)
    I was prepared for the worst, because it makes sense that the series would get progressively darker, but then...snogging in the hallways? Boy/girl drama? I adore the love triangles and the Slughorn parties here. Broken hearts and magic! Horcruxes, Voldy history, journeys into the pensieve. SNAPE BETRAYAL. As long as Albus was around, everything felt safe, but this was a heck of a way to set the stage for Book 7. The funeral passage and Fawke's last flight always makes me teary *Raises Wand*
  3. Deathly Hallows
    Great finale. Love: Ron + Hermione, Harry + Ginny, the trio treking across country, the mystery, problem solving, high stakes, character redemption/evolution. But the DEATHS: Dobby slays me, and it's just the tip of the iceberg. The final battle at Hogwarts is perfection--it comes full circle and we get to revisit so many important scenes (the Chamber, the Room of Requirement). McGonagal *fist pump*. The epilogue is so satisfying. Harry Potter lives on, even if it's just in our imagination.
  4. Goblet of Fire
    The Quidditch World Cup. THE TRIWIZARD TOURNAMENT! Boom-shaka-laka. Innocent crushes, Rita Skeeter, Mad Eye Moody, gigantic bubble baths, dragons, mermaids, mazes. The end of this book is where IT STARTS TO GET REAL. Cedric's is the first death that we experience and it's a terrible hint of what's coming. Although this climaxes with a typical Harry vs. Voldy battle, Harry doesn't "win." We see the resurgence of the Death Eaters, find out what happened with Wormtail, and Voldermort RISES AGAIN.
  5. Order of the Phoenix
    MIXED FEELINGS. Love Grimmauld Place, the Room of Requirement, the OOTP, Dobby, SPEW, Ron (after being kind of stupid in GOF) having Harry's back, Fred + George's epic exit, Peeves, Luna Lovegood, Thestrals, McGonagal etc. Hate Harry's adolescent 'tude, Umbridge, relative absence of Quidditch (but Ron + Ginny make the team), Dumbly's coldness, etc. The ending is like a punch in the stomach. I get what Rowling is doing, but it doesn't fill me with the warm fuzzies in the way the other books do.
  6. Philosopher's Stone
    Magical and surprising and you want to dive right in. Harry is transported to this phenomenal alternate reality and we get to journey alongside him. Platform 9 3/4, The Great Hall, Halloween celebrations (pumpkin juice--sounds delicious), magical classes, moving portraits, Quidditch, Christmas at Hogwarts, changing staircases, post by owls, what fun! This book is sweet and innocent, as it should be, and I love it all. And re-reading is so sweet: everything takes on a special significance.
  7. Chamber of Secrets
    It's not that I have anything against this book, but I can't think of a reason to rank it any higher. You've got demon diary that sets the stage for Horcruxes, Tom Riddle, flying cars, the Weasleys + the Burrow, Fawkes, Gilderoy Lockhart, and the whole school hating Harry (which happens a lot, all things considered)... Frankly, I can't believe that a bunch of prepubescents figured out this mystery before anyone else. This book is great, just not my fave.